user function
Applies to: 
Databricks SQL Databricks Runtime 13.3 LTS and above
Returns the user executing the statement. This function is an alias for current_user.
Note
The SQL standard differentiates between CURRENT_USER and SESSION_USER.
In Databricks SQL and Databricks Runtime 14.1 and above you should use SESSION_USER instead of CURRENT_USER or USER.
Syntax
user()
Arguments
This function takes no arguments.
Returns
A STRING.
The braces are optional.
Examples
> SELECT user();
user1
> SELECT user;
user1